The "250EYE MV Ballast draws 6.85 amps max at 120v powering a 250w lamp" means that at startup it uses up to 6.85 amps. That may last seconds.
A conventional ballast has to build up a 3 to 5KV jolt to start a lamp. Other electronic ballasts do the same thing to the bulb, just use a different method to achieve it. IceCap has a method of using a high frequency 1KV signal to start the lamps. As the lamp warms up the power to it increases. That's one reason an IceCap can be 100 feet away from the MH bulb, 1KV travels better than 5KV. The other issue I'm aware of is the HZ (on/offs per second) the bulbs run. Conventional and most other run at 60 or 120 HZ, so that many times per second on and off. IceCap runs at 15,000 to 20,000 HZ (15-20KHz) and therefore just stays on.
Last time I spoke to Iwasaki's R&D MH specialist he thought our method would tend to increase the lamps life.
As far as output, the IceCap MHI runs at 285 watts with 97% of that going to the bulb. That's why the ballasts run cool. Maybe someone has run output comparisons and can comment on the light.
Andy